Hello,
Thank you. It worked now. x=x+1 must have the same indention als the if then and the return. Roelof > Subject: Re: [Tutor] prime test problem > From: evert....@gmail.com > Date: Sat, 21 Aug 2010 19:24:51 +0200 > CC: tutor@python.org > To: rwob...@hotmail.com > > > Hello, > > > > I tried it with this simple programm > > > > def is_prime(n): > > x=2 > > while x <= int(n**0.5)+1: > > if n % x == 0: > > return False > > If your while condition is True, you get into the loop. > Inside the loop, however, you never change anything that could change the > condition (ie, neither x nor n get changed). > So the while condition stays the same, ie, True, and you loop indefinitely. > > > > x=x+1; > > Ah, but here you actually change something so that the while condition could > become False. Sadly, this statement is outside the loop (hint hint). > > > > > > return True > > > > x=is_prime(7) > > if x==True: > > print 7, "is een prime getal" > > else : > > print 7, "is geen prime getal" > > > > > > But this one gets in a indefinitive loop. > > Try to mentally follow the logic of the loop. > Or use print statements and some small, easily checkable, numbers (prime and > non-prime) to see what happens. > Print statements (functions, if you're on Python >= 3) are a simple, but at > times extremely quick and useful way to debug scripts. > > Ah yes, and either use "is een priemgetal" or "is a prime number", not a mix > of both (sorry, couldn't help myself ;-). > > > Evert > > > > > > > Roelof > > > > > > > From: st...@pearwood.info > > > To: tutor@python.org > > > Date: Sun, 22 Aug 2010 02:49:26 +1000 > > > Subject: Re: [Tutor] prime test problem > > > > > > On Sun, 22 Aug 2010 12:41:03 am Roelof Wobben wrote: > > > > Hello, > > > > > > > > I know. > > > > I have read them all I believe > > > > > > You've read all 64 million pages that Google finds? Wow, you must be a > > > fast reader! Well done! > > > > > > > but I can't see how I can convert the > > > > algebra to a working programm. > > > > > > Have you *tried*? > > > > > > Perhaps you should try something a little bit less ambitious. Write a > > > program to test whether a number is divisible by 3. Then write a > > > program to test whether a number is divisible by 3 or 5. Then write a > > > third program to test whether a number is divisible by 3, 5 or 7. > > > > > > Then generalise that third program. > > > > > > Off you go. Come back when you have some code. Even if it isn't working > > > code, at least try something. > > > > > > > > > > > > -- > > > Steven D'Aprano > > > _______________________________________________ > > > Tutor maillist - Tutor@python.org > > > To unsubscribe or change subscription options: > > > http://mail.python.org/mailman/listinfo/tutor > > _______________________________________________ > > Tutor maillist - Tutor@python.org > > To unsubscribe or change subscription options: > > http://mail.python.org/mailman/listinfo/tutor >
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